Background and Objectives: This is the first study to examine the role of monocyte distribution width (MDW) in predicting sepsis after cardiovascular surgery. Methods: This study included 43 consecutive patients who had undergone cardiovascular surgery between July 2021 and July 2022. All patients were examined at the following three time points (TPs): preoperative period (TP1), postoperative at 24 h (TP2), and discharge (TP3). SOFA score, leukocyte count, neutrophil-to-lymphocyte ratio (NLR), MDW, C-reactive protein (CRP), and procalcitonin (PCT) levels were tested at each TPs. The Sepsis-3 criteria were used to diagnose patients with sepsis. Results: The mean values of all variables (leukocyte count, NLR, MDW, CRP, and PCT levels) were significantly higher at TP2 and TP3 than at TP1 (p < 0.05). All these values were significantly higher at TP2 than at TP3 (p < 0.05). Patients with sepsis had significantly higher mean values for leukocyte count, NLR, MDW, CRP, and PCT levels than those without sepsis (p < 0.05). There was a significant correlation between MDW and inflammatory markers (CRP, PCT, and NLR) during the three time periods (p < 0.05). According to the ROC analysis, the optimal MDW cutoff value with the highest sensitivity and specificity for predicting sepsis in the postoperative period was 20.5. Conclusions: Our findings indicate that elevated MDW levels may be a valuable predictor of sepsis in patients following cardiovascular surgery.

Background/Objectives: Tricuspid valve surgery carries a high risk of postoperative acute kidney injury (AKI) due to pre-existing right ventricular dysfunction and congestive end-organ remodeling. We aimed to evaluate the incidence and predictors of postoperative AKI, with particular focus on the prognostic value of the TAPSE/sPAP index. Methods: This retrospective, single-center study evaluated adult patients who underwent tricuspid valve surgery (isolated/concomitant) between 2010 and 2025. The primary outcome was postoperative AKI of any stage, defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Predictors were identified using a pre-specified multivariable logistic regression model including baseline estimated glomerular filtration rate (eGFR), cardiopulmonary bypass time, and EuroSCORE II; TAPSE/sPAP associations with severe renal outcomes were assessed univariably and presented as exploratory. Results: Of 80 patients, postoperative AKI occurred in 32 (40.0%), with 16 (20.0%) requiring renal replacement therapy. The pre-specified multivariable model discriminated any-stage AKI (AUC 0.86, 95% CI 0.77–0.94). Lower baseline eGFR (adjusted OR 1.82 per 10 mL/min/1.73 m² decrease, p < 0.001) and higher EuroSCORE II (adjusted OR 1.53 per point, p = 0.03) were independent predictors. The TAPSE/sPAP index was not associated with any-stage AKI (p = 0.42), but lower values predicted advanced renal outcomes, including KDIGO stage ≥ 2 AKI (OR 2.11, p = 0.03) and the requirement for renal replacement therapy (OR 2.71, p = 0.01). Outcomes did not differ between isolated (n =14) and combined procedures (n = 66; AKI 35.7% vs. 40.9%, p = 0.77). Conclusions: Lower preoperative eGFR and higher EuroSCORE II independently predict any-stage postoperative AKI. In univariable analysis, the TAPSE/sPAP index identified the subgroup with severe renal outcomes; this exploratory finding requires prospective validation. Whether perioperative renal protection depends on addressing right-sided filling pressures rather than augmenting forward flow alone requires prospective testing.